<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    *{
      margin: 0;
      padding: 0;
    }
    .page{
      height: 200px;
      width: 100%;
    }
    .left, .right{
      width: 200px;
      height: 200px;
      background: #1ae216;
    }
    .content{
      height: 200px;
      background-color: #e0c230;
    }

    .page{
      display: grid;
      grid-template-columns: 200px auto 200px;
    }
  </style>
</head>
<body>
  <div class="page">
    <div class="left">广告位</div>
    <div class="content">主要内容</div>
    <div class="right">广告位</div>
  </div>
</body>
</html>